Greyson explains the purposes of his "NDE Scale"

I wanted to bring some logical order to the study of near-death experiences. To tackle this problem, I developed the NDE Scale in the early 1980s as a way to standardize what we mean by the term “near-death experience.” I started with a list of the eighty features most often mentioned in the literature on NDEs and sent this list to a large sample of experiencers. Then, through a series of repeated assessments by experiencers and other researchers, with the help of statistical analyses, I whittled the scale down to a more manageable list of sixteen features.

So the NDE Scale is not a measure of how deeply an experiencer may be affected. It’s simply a tool that researchers can use to make sure they’re investigating the same experience. And in the thirty-eight years since it was first published, the NDE Scale has stood the test of time, having been translated into more than twenty languages and used in hundreds of studies around the world.

Twenty years after this scale was published, and long after it had become accepted as the standard tool of NDE researchers worldwide, I was challenged by two skeptical scholars I didn’t know: Rense Lange, a statistician from Southern Illinois University School of Medicine, and Jim Houran, a psychologist then at the University of Adelaide in Australia. These scholars had no previous interest in NDEs but were applying a complicated statistical test to various scales that had been developed by other researchers—and in the process “debunking” some of them. They wanted me to give them the raw responses on the scale that I had collected from around three hundred people who had come close to death and let them carry out their sophisticated statistical test on the data to see whether the NDE Scale was valid. 

Apprehensive, I had reservations about working with them. I’d already put years of work into this scale, and it had become accepted by scholars around the world. I wasn’t familiar with the statistical test they wanted to carry out. I didn’t know whether it was a good test, and whether my scale would hold up under it. What if the scale failed the test? Would it cast doubt on all my work with NDEs? Would it ruin my credibility and my career as a scientist? 

On the other hand, if the NDE Scale was faulty, I certainly wanted to know that! How could I refuse to share my data and put my scale to the test? If I was truly a skeptic, how could I be skeptical of other people’s ideas but not my own? I’d met too many academics who called themselves “skeptics” but refused to look at any evidence that might challenge their own beliefs. Could I swallow my pride—and my fear of failing—and expose my data to an independent test? That’s what intellectual honesty required. That’s what a true skeptic would do.

That’s what my father, had he still been alive, would have wanted me to do. I handed over all my data on the NDE Scale, the responses of hundreds of people who’d had near-death experiences and waited for the results from Rense and Jim. As the months went by, I had many fitful nights second-guessing my decision to subject my work to that scrutiny. But each morning, in the light of day, I knew that it was the right thing to do. To my great relief, their analysis ended up confirming the validity of the NDE Scale. 

It showed that the scale measured one consistent experience that was the same for men and women and for people of all ages, across many cultures. NDE Scale scores were the same no matter how many years had passed since the experience. I heaved a huge sigh of relief. My NDE Scale—and by extension NDEs themselves—had been given the stamp of credibility by a team of skeptics who not only had no stake in near-death experiences but would have been happy to discredit them.

Greyson, Bruce. After (pp. 54-56). St. Martin's Publishing Group. Kindle Edition.